Adjustable Volume Piston System

ABSTRACT

An adjustable volume gas piston system for a pneumatic reloading firearm includes a gas block having an anchoring portion for anchoring along the barrel. The gas block also includes a chamber portion in pneumatic connection with the barrel. The chamber portion has one end pointing toward the muzzle and another end pointing away from the muzzle. A plug having a bore is affixed to the chamber portion at the forward end. The second end has an opening to allow travel of a gas pin but retains a gas pin head in the chamber portion, biasing it toward the first end. Upon firing the firearm, the volume of the bore causes a pressure delay on the gas pin head, thereby delaying the timing of pneumatic reloading.

This application claims the benefit of the priority filing date of U.S.provisional application No. 61/920,454, filed on Dec. 23, 2013.

BACKGROUND

Gas-operated automatic reloading systems for firearms are known in theart. Typically, these systems divert a portion of high pressure gasgenerated from firing, using it to eject the bullet casing and chamber anew cartridge. Gas blocks are used to control the portion of gas used bythe reloading system. Since unregulated pressure can destroy firearmcomponents, gas blocks limit the amount of gas traveling into thereloading system to a predetermined level. Some gas blocks areadjustable, allowing users to change the quantity of gas as firingcharacteristics change due to altering the type of ammunition, or carbonand other material building up in the firearm form repeated firing.

Typical gas-operated automatic reloading systems port highly pressurizedgas through a gas block and tube, bringing it to impinge directly on thebolt carrier, providing the energy necessary for the carrier to ejectthe spent casing and chamber a new cartridge. These direct impingementsystems must be cleaned frequently. Gasses generated from firing havehigh concentrations of carbon, sulfates, and other materials that formaccretions on firearm parts, adversely affecting firing characteristics.

Gas piston automatic reloading systems are used as an alternative toavoid contaminating the parts of the firearm. Piston systems employ agas piston (also known as a ‘gas pin’) that bridges the gas block andthe upper receiver. Upon firing, gas travelling into the gas blockimpinges immediately on a piston head of the gas pin, pushing the gaspin into the receiver to activate the reloading action. In this manner,gas piston systems avoid fouling internal components of the firearm, butcan present a timing problem.

When a cartridge is fired, extremely high temperature and pressure gasgenerated between the bullet and the casing cause the casing to deformand swell in the chamber. Using softer, thermal conducting metals suchas brass for casings help prevent them from lodging in the chamber, butrequire a brief dwell time allowing a spent casing to cool and shrinkbefore it can be ejected. In direct impingement systems, the brief lagas sufficient pressure builds across the system to move the bolt carrierprovides sufficient dwell time. In gas piston systems, the immediacy ofthe gas acting on the piston head and resulting mechanical reloadingmovement sometimes fails to allow sufficient dwell time, resulting in ajammed system.

It is therefore an object of the present invention to provide a gaspiston system that avoids residue contamination from firing gases, butalso provides sufficient dwell time to avoid malfunctions. Anotherobject of the invention is to provide an adjustable volume gas blockthat allows a user to adjust the dwell time of the reloading system to adesired timing. Another object of the invention is to provide anadjustable volume gas block integrating dwell time adjustments and gaspressure adjustments. These and other objects are more fully developedin the following description claim and drawings.

SUMMARY

An adjustable volume gas piston system for a pneumatic reloadingfirearm, preferably having an elongated barrel with a muzzle isdisclosed. The primary component of the system is a gas block. The gasblock includes an anchoring portion that anchors along the barrel,preferably surrounding the barrel. Anchoring pins may be included at thebottom of the anchoring portion in one embodiment, and in another,notches on the barrel may ensure the anchoring portion stays inposition.

The gas block also includes a chamber portion, preferably above theanchoring portion. The chamber portion is in pneumatic connection withthe barrel, allowing gasses from firing the firearm to travel from theinterior of the barrel into the chamber portion. Preferably, the chamberportion has a first end toward the muzzle and a second end away from themuzzle. In this manner, the chamber is oblong, oriented in the directionand at the position of a gas pin of the reloading system.

The first end of the chamber portion is open and adapted to receive aplug. The plug includes a bore and is therefore predominantly hollow,thereby forming a chamber in the chamber portion. The plug is affixed tothe chamber at the first end in a manner that prevents it from becomingdislodged when the firearm is fired. The second end includes an openingthat receives the gas pin. The gas pin preferably includes a gas pinhead that is retained in the chamber portion, in one embodiment becausethe gas pin head is to large to travel through the opening, and biasedtoward the first end. A spring located in the chamber portion betweenthe opening and the gas pin head may serve as a biasing mechanism.

Upon firing the firearm, the volume of the bore produces a pressuredelay on the gas pin head. The delayed pressure results in a slighttiming differential between firing and activation of the gas pin andpneumatic reloading. An important feature of the chamber portion of thegas block is that it is adjustable, thereby rendering the volume of thechamber portion and the timing differential adjustable. The principalway this adjustability is accomplished is by rendering the plug able tomove relative to the chamber portion. In one embodiment the plug hasthreads that rotatably engage complimentary threads on the chamberportion. In this embodiment, the plug may closely resemble a screwhaving a head for engaging a fastening mechanism that turns the plug, aseries of threads near the shoulder of the head, and an enlarged hollowplug body that forms part of the chamber in the chamber portion.

Adjusting the position of the plug relative to the chamber portionchanges the volume of the chamber portion. Because the plug is movable,and due to pressures created by vibration and pressurized gas enteringthe chamber portion, over the course of firing several rounds the plugmay have a tendency to change its orientation, thereby altering thevolume of the chamber portion. To solve this problem, the plugpreferably includes a biased stop mechanism to preserves the plug'sposition and thereby the volume of the chamber portion after positioningthe plug to create a predetermined volume.

Preferably the biased stop mechanism is a bearing pressed into a biasedposition on the plug and a complimentary seat for the bearing on the gasblock. In one embodiment, for ease of manufacturing, a bore is createdthrough the head of the plug. The bore is sized to accommodate a bearingcylinder. The bearing is retained in the cylinder along with a springthat pushes the bearing to an open end of the cylinder. By inserting thecylinder a certain distance into the bore, a hemispherical portion ofthe bearing will extend away from the head of the bore.

In this embodiment, the gas block includes a screw set adjacent the plughead. The screw set includes a seat to receive the bearing. In thismanner, as the plug head and bearing are rotated causing the bearing toencounter the screw set, the bearing will ‘snap’ into the seat, therebyretaining the plug in its position. In another embodiment the timing ofthe threads on the plug may be set so that when the plug is adjusted toits maximum point of insertion into the chamber portion, the bearingaligns with the seat.

When loosening the plug to adjust the volume of the chamber portion andthe timing of the automatic reloading system, the bearing willperiodically seat in the screw set, allowing users to set the gas blockat a variety of pressures. In order to provide a safety, should firingvibration and pressure cause the bearing to unseat itself from itsposition, the screw set may include a second seat for catching thebearing and holding it in position prior to adjustment by a user.

The bore in the plug accounts for part of the gas chamber in the chamberportion. The remainder of the chamber is made up of the gas pin head andany space between the plug and the gas pin head. In one embodiment, thegas pin head may be biased to abut the plug. Preferably, therelationship between the chamber portion and the gas pin head is not apneumatic seal and some minimal quantity of gasses are capable oftravelling past the gas pin head upon firing. To introduce turbulenceinto gas travelling along the gas pin head, circumferential channels maybe incorporated into the gas pin head. In another embodiment, the gaspin head may have a concave surface facing the bore to enlarge thechamber.

The gas pin head is locked into the chamber portion by an opening in thesecond end that only permits travel of the shaft of the gas pin.Preferably, the opening may include smaller cut-outs or other openingsto allow gasses to pass between the gas pin head and the chamberportion, thereby exiting out the second end. The cut-outs or openings onthe second end are not the primary exit for gasses produced by firinghowever. In one preferred embodiment, an exhaust port may be locateddirection on the chamber portion.

Typically the exhaust port will be obscured by the gas piston head priorto firing, either covered by the gas piston head itself, or locatedbetween the gas piston head and the second end. When the gas piston headis pushed toward the second end upon firing, the gas piston head willclear the exhaust port allowing pressurized gasses to exit the gasblock. The other means for gas to exit the gas block is to travel backdown into the barrel. To adjust the gas quantity and pressure travellinginto the gas block upon firing, the gas block may also include animpinging screw between the barrel and the chamber portion for closingthe pneumatic connection.

In order to adjust an automatic reloading firearm, including a gas pinand barrel, a gas block is first provided, the gas block having ananchoring portion and also having a chamber portion that defines achamber. The gas block is installed on the barrel in a manner providinga pneumatic communication through the gas block between the chamber andthe barrel. The chamber is preferably open at an end toward the barrelmuzzle, and a plug having a bore is inserted into the open end of thechamber. Preferably the bore in the plug also defines a chamber. Priorto inserting the plug, a user preferably inserts a gas pin having a gaspin head into the chamber, such that the shaft of the gas pin extendsthrough an opening in a second end of the chamber portion opposite thefirst end. Once the gas pin and plug are adjusted, the firearm may befired, thereby causing a delay in the automatic reloading action of thegas pin.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a side view of a first embodiment adjustable volume gas blockinstalled on a firearm.

FIG. 2 is a perspective view of an adjustable volume gas block installedon the firearm barrel.

FIG. 3 is an exploded view of a post screw and washers.

FIG. 4 is a cut-away view of an adjustable volume gas block with anexpanded chamber volume.

FIG. 5 is a cut-away view of an adjustable volume gas block with areduced chamber volume.

FIG. 6 is an exploded view of the first embodiment adjustable volume gasblock.

FIG. 7 is a side view of a second embodiment gas block and gas pistonsystem installed on an automatic reloading firearm.

FIG. 8 is an enlarged side view of the second embodiment gas block.

FIG. 9 is a perspective view of a chamber screw according to the secondembodiment.

FIG. 10 is a perspective view of a cylinder having a biased bearingmechanism.

FIG. 11 is a front partial cut-away view of the second embodiment gasblock.

FIG. 12 is an exploded view of the second embodiment gas block.

FIG. 13 is a cut-away view of the second embodiment adjustable volumegas block with an expanded chamber volume.

FIG. 14 is a cut-away view of the second embodiment adjustable volumegas block with a reduced chamber volume.

FIG. 15 is a cut-away side view of a gas pin of the second embodimentadjustable gas block impinging on the tombstone of an automaticreloading firearm.

FIGS. 16A, 16B, and 16C are cut away side views of chamber screws havingdifferent bore sizes.

FIG. 17 is a side view of the second embodiment adjustable volume gasblock covered by a hand guard on a firearm.

REFERENCE NUMBERS

-   -   10. First Embodiment Gas Block    -   12. Firearm    -   14. Anchoring Portion    -   16. Barrel    -   18. Chamber Portion    -   20. Gas Piston    -   22. Set Screw    -   24. Gas Passage    -   26. Bearing Mechanism    -   28. Bearing    -   30. Longitudinal Slots    -   32. Post Screw    -   34. Screw Head    -   36. Slot    -   38. Threaded Portion    -   40. Slanted Shoulder    -   42. Post    -   44. Washers    -   46. Retainer    -   48. Piston Head    -   50. Concave portion    -   52. Piston Head Slots    -   54. Chamber Portion Slots    -   52. Larger Chamber Portion    -   54. Smaller Chamber Portion    -   56. Spring    -   58. Pin    -   100. Second Embodiment Gas Block    -   102. Gas Operated Reloading System    -   104. Gas Pin    -   106. Tombstone    -   108. Anchoring Portion    -   110. Chamber Portion    -   112. Impinging Screw    -   114. Chamber Screw    -   116. Portal    -   118. Broadened Slot    -   120. Screw Head    -   122. Bore    -   124. Socket    -   126. Bearing Mechanism    -   128. Cylinder    -   130. Open End    -   132. Retaining Portion    -   134. Bearing    -   136. Spring    -   138. Screw Set    -   140. Divot    -   142. Gas Pin Head    -   144. Channels    -   146. Concave Face    -   148. Relief Port    -   150. Gas Pin Spring    -   152. Chamber Exhaust    -   154. Bore    -   156. Hand Guard

DESCRIPTION

Referring to FIG. 1, an adjustable volume gas block 10 is shown affixedto a gas-operated reloading firearm 12. The gas block 10 comprises ananchoring portion 14 which fits around the barrel 16 of the firearm 12and is in fluid communication with the interior (not shown) of thebarrel 16. A chamber portion 18, which comprises an elongated structure,is formed atop the anchoring portion 14. In a preferred embodiment, thechamber portion 18 extends longitudinally back along the barrel 16 fromthe anchoring portion 14.

Referring to FIG. 2, the gas block 10 comprises two mechanisms forcontrolling the gas pressure coming from the barrel 16, allowing usersto precisely control the action of the gas piston 20 of the firearm 12when reloading. The first, a bearing mechanism 26 includes a set screw22 designed to impinge the gas passage 24 (see FIGS. 4 and 5) betweenthe barrel 16 and the chamber portion 18. The bearing mechanism 26 urgesa bearing 28 (see FIG. 6) against longitudinal slots 30 (see FIG. 6) onthe set screw 22 to preserve it in a desired position. The second,adjustable volume mechanism includes a post screw 32 anchored in thechamber portion 18 which, with the addition of one or more washers 44(see FIG. 3), reduces the volume in the chamber portion 18.

Referring to FIG. 3, the post screw 32 includes a screw head 34, whichpreferably includes a conventional engaging mechanism, such as a slot 36or similar mechanism for engaging a tool (not shown) such as a screwdriver. Although a slotted screw head 34 is shown, any type of engagingmechanism allowing the post screw 32 to be turned is contemplated. Thepost screw 32 also includes a threaded portion 38 for engaging thechamber portion 18 of the gas block 10 and to hold the post screw 32 inposition. Preferably, the post screw 32 engages the chamber portion 18to the front of the gas block 10, opposite where the gas piston 20 exitsthe chamber portion 18. The post screw 32 may also include a slantedshoulder 40 for creating a tight seal against the chamber portion 18.

Still referring to FIG. 3, the post screw 32 includes a post 42extending from the screw head 34, through the chamber portion 18. Thepost 42 is substantially narrower than the chamber portion 18 and isadapted to receive one or more washers 44 which will fill the chamberportion 18 once inserted on the post 42. Optionally, a retainer 46 maybe included to hold the washers 44 in place.

Referring to FIGS. 4 and 5, two cross sectional views of the gas block10 are shown having two different pressure settings. Referring to FIG.4, the post screw 32 has been inserted into the chamber portion 18, withthe threaded portion 38 and slanted shoulder 40 engaging complimentaryareas of the chamber portion 18 to form a substantially air-tight seal.The post 42 extends backward, through the chamber portion 18 to engagethe piston head 48 of the gas piston 20.

Still referring to FIGS. 4 and 5, the piston head 48 may include aconcave portion 50, which serves to accommodate the post 42 as well asprovide additional chamber area in the chamber portion 18. Preferably,the piston head 48 also includes piston head slots 52, which serve tointroduce turbulence into gasses travelling around the piston head.Beyond the piston head 48, chamber portion slots 55 allow excess gassesto escape the chamber portion 18 around the gas piston 20. With only thepost 42 occupying the chamber portion 18 between the piston head 48 andthe screw head 34, a large volume allows more gas to build up in thechamber portion 18 before urging the gas piston 20 to reload the firearm12.

Referring to FIG. 5, the set screw 22 is inserted into the chamberportion 18 in the same manner as FIG. 4, but with washers 44 installedon the post 42 of the set screw 22. In this manner, the chamber portion18 has less volume and allows less gas to build up in the chamberportion 18 before urging the gas piston 20 to reload the firearm 12.Notably, the interior of the chamber portion 18 includes a largerchamber 52 and a smaller chamber 54. The larger chamber 52 is sized toaccommodate the washers 44, while the smaller chamber 54 is sized toexclude the washers 44, and is connected to the gas passage 24. In thismanner, the washers 44 are forced toward the screw head 34 by gaspressure, and are prevented from entering the smaller chamber 54 andoccluding the gas passage 24. The chamber portion 18 also includes anexit portal 55 allowing excess gasses to exit the chamber portion 18

FIG. 6 shows an exploded view of the gas block 10. The anchoring portion14 of the gas block 10 is installed over the barrel 16 of a firearm 12(not shown), with the chamber portion 18 extending along the barrel 16to the rear. The bearing mechanism 26 is assembled by inserting the setscrew 22 into the gas block 10 and inserting the bearing 28 to engagethe longitudinal slots 30. In one embodiment, the bearing may be held inplace by a spring 56, which is anchored in position by a pin 58.

Still referring to FIG. 6, the gas piston 20 is inserted into thechamber portion 18, until the piston head 48 is seated in the smallerchamber 54 (see FIGS. 4 and 5). Preferably a spring (not shown) will beinserted on the gas piston 20 and installed behind the piston head 48 toprovide recoil in the chamber portion 18. With the piston head installedin the smaller chamber 54, a series of washers 44, and optionally aretainer 56 may be installed on the post 42 of the post screw 32. Thepost screw 32 is then installed in the chamber portion 18 and tightenedin position using the threaded portion 38 and slot 36, such that theslanted shoulder 40 engages a complimentary surface on the chamberportion 18.

In operation, the gas block 10 may be assembled without washers. In thismanner, the bearing mechanism is set to a desired position. When thefirearm is fired, gasses passing through the gas passage enter thechamber portion 18 filling the smaller chamber portion 54 and largerchamber portion 52. Due to the enlarged chamber portion 18, andincluding the concave portion 50 of the piston head 48, a delay, causedby gas filing the chamber portion 18 will slow activation of the gaspiston 20.

To reduce the delay, the post screw 32 is removed and one or morewashers 44 are installed on the post screw 34. The washers take up aportion of or all of the larger chamber portion 52, such that when thefirearm is fired, gas more quickly fills the smaller chamber portion 54and activates movement of the gas piston 20. Various degrees of pressuremay be achieved by only partially filling the larger chamber portion 52with a desired number of washers 44 and by making correspondingadjustments with the bearing mechanism.

Referring to FIGS. 7 through 17, a second embodiment gas block is shownand described. FIG. 7 shows the second embodiment gas block 100 affixedto the barrel 16 of the firearm 12 having a gas-operated reloadingsystem 102. The second embodiment gas block 100 is similar to the firstembodiment gas block 10 in that it engages a gas pin 104, which engagesthe tombstone 106 of the bolt group for reloading the chamber (notshown).

Referring to FIG. 8, a side view of the second embodiment gas block 100is shown. Like the first embodiment gas block 10, the second embodimentgas block 100 includes an anchoring portion 108 and a chamber portion110. The second embodiment gas block 100 also includes an impingingscrew 112 for impinging the gas passage (not shown) between the barrel16 and the chamber portion 110. A chamber screw 114 is installed intothe chamber portion 110 of the gas block 100. The impinging screw 112 ispreferably incorporated below the chamber screw 114.

Referring to FIG. 9, the chamber screw 114 is shown. The chamber screw114 includes a portal 116 for allowing expelled gas to enter the chamber110 from the barrel 16 (see FIG. 8). The portal 116 includes a broadenedslot 118 on one end. The purpose of the broadened slot 122 is to allowgas to travel from the barrel 16 into the chamber 110 when the chamberscrew 114 is in any of its set positions. The chamber screw 114 alsoincludes a screw head 120 with a bore 122 extending through it.

The screw head 120 preferably includes means for turning or adjustingthe position of the screw 114. In the illustrated embodiment a hexagonalAllen wrench socket 124 is shown, although other mechanisms such asslotted screw heads are contemplated. The screw head 120 also includes athreaded portion 124 for engaging the chamber portion 110 of the gasblock 100.

Referring to FIG. 10, a bearing mechanism 126 is shown. The bearingmechanism 126 comprises a cylinder 128, which is inserted into the bore122 on the chamber screw 114 (see FIG. 9). The cylinder 128 ispreferably hollow with one open end 130. The open end 130 of thecylinder 128 includes a retaining portion 132 that retains a bearing 134in the cylinder 128. In one embodiment, the retaining portion 132 maypresent a conical surface.

Referring to FIG. 11, a front view of the second embodiment gas block100 is shown in partial cut-away view (see FIG. 8, cut-away reference11). In this view bearing mechanism 126 is shown incorporated into thebore 122 of the screw head 120. Shown in this view, a spring 136 isvisible biasing the bearing 134 out of the bearing mechanism 126 andagainst the retaining portion 116. The bearing mechanism 126 issubstantially flush with the screw head 120, allowing a portion of thebearing 134 to extend past the screw head 120.

Still referring to FIG. 11, a screw set 138 is proximal the screw head120 when the chamber screw 114 is installed in the chamber portion 110.As the biased bearing 134 rotates adjacent the screw set 138, it ispressed back flush with the screw head 120 under force. The screw set138 includes divots 140 for accommodating the bearing 134. In thismanner, with the bearing disposed in a divot 140, it retains the chamberscrew 114 in a predetermined position, according to a predeterminedchamber portion 110 volume. In the illustrated embodiment, two divots140 are shown to present a safety. If the bearing 134 is driven underthe force of firing from the first divot 140, the second divot 140 willreceive it and prevent the chamber screw 114 from rotating further.Preferably, the timing of the threads (not shown) in the chamber portion110 and the threads 124 on the chamber screw 126 are such that thebearing 134 will be located in a divot 140 when the chamber screw 114 isin a fully closed position abutting the chamber portion 110.

Referring to FIG. 12, an exploded view of the second embodiment gasblock 100 is shown. The gas pin 104 extends through the chamber 110,terminating in a gas pin head 142. The gas pin head 142 is substantiallythe circumference of the chamber portion 110 interior, but does notcreate an air tight seal. Rather, several channels 144 are located onthe gas pin head 142 to generate turbulence in any gas flow travelingpast the gas pin head 142 to provide a cushioning effect. The gas pinhead 142 also has a concave face 146, which increases the total volumeof the chamber portion 110. The chamber 110 also includes a relief port148, which allows excess gas to escape the chamber portion 110 once thegas pin head 142 reaches a terminal position at the end of the chamberportion 110 opposite the chamber screw 114.

Referring to FIGS. 13 and 14, the second embodiment gas block 100 isshown in a condition prior to firing (FIG. 13) and during firing (FIG.14). Referring to FIG. 13, prior to firing, the chamber screw 114 hasbeen turned into the chamber portion 110 to a position of desiredpressure. In the illustrated embodiment, the impinging screw 112 hasbeen set to allow gases from firing to travel freely into the chamberportion 110. The chamber screw 114 has also been set to a predeterminedposition using the screw set 140. In the illustrated embodiment, thechamber screw 114 is fully inserted into the chamber portion 110 suchthat it abuts the gas piston head 142. When the firearm is fired, gassesenter the chamber and exert pressure according to the arrows.

Referring to FIG. 14, after firing, gasses press against the chamberscrew 114, which is anchored in place, and the gas pin head 142, forcingthe gas pin 104 rearward against the tombstone 106 (FIG. 7). To allowpressure relief, some gas may make its way around the gas pin head 142,encountering the channels before exiting through the chamber exhaust152. The major portion of the gas produced from firing forces the gaspin head 142 backward, compressing the spring 136, until the gas pinhead 142 clears the relief port 148 and exits the chamber 110.Preferably the relief port 148 is positioned on the chamber 110 suchthat the gas pin head 142 clears the relief port 148 when the gas pinspring 150 is in a fully compressed position. Any remaining gases in thechamber 110 can also travel back into the barrel 16 and exit before thenext round is fired.

Referring to FIG. 15, the opposite end of the gas pin 104 is shown whereit engages the tombstone 106 on the firearm 12. By pushing back thetombstone, the gas pin 104 causes the bolt group (not shown) to movethrough its operating cycle. Referring to FIGS. 16A-16C, several sizesof chamber screws 114 are shown with different bore 154 sizes accordingto user preference. The different bore 154 sizes establish differentvolumes in the chamber portion 110. While turning the chamber screw 114in the chamber 110 allows fine tuning of the gas block 100, in certaininstances a much larger or smaller volume is desired. In theseinstances, a chamber screw 114 having an enlarged or reduced bore 154 iscontemplated.

Referring to FIG. 17, a hand guard 156 is shown attached to the firearm12 over the gas block 100 (not shown). Due to the reduced size of thegas block 100 compared to other, larger systems, the gas block 100 neednot be removed prior to installation of the hand guard 156. This allowsthe gas relief characteristics of the gas block 100 to be used evenwhile the hand guard 156 is in place.

While particular forms of the invention have been illustrated anddescribed, it will also be apparent to those skilled in the art thatvarious modifications can be made without departing from the spirit andscope of the invention. Accordingly, it is not intended that theinvention be limited except by the full breadth and scope of theappended claims.

What is claimed is:
 1. An adjustable volume gas piston system for apneumatic reloading firearm having a barrel with a muzzle, comprising: agas block having an anchoring portion for anchoring along the barrel; achamber portion in pneumatic connection with the barrel, the chamberportion having a first end proximal the muzzle and a second end distalfrom the muzzle; a removable plug having a bore, the plug affixed to thechamber portion at the first end; and the second end having an openingto receive a gas pin, wherein the gas pin comprises a gas pin headretained in the chamber portion and biased toward the first end, andwherein upon firing the firearm, the volume of the bore causes apressure delay on the gas pin head, thereby delaying the timing ofpneumatic reloading.
 2. The gas piston system of claim 1 wherein theplug moves relative to the chamber portion.
 3. The gas piston system ofclaim 1 wherein the plug comprises a threaded member that rotatablyengages the chamber portion.
 4. The gas piston system of claim 1 whereinadjusting the position of the plug changes the volume inside the chamberportion.
 5. The gas piston system of claim 1 wherein the plug comprisesa biased stop mechanism that preserves the volume of the chamber portionat a predetermined volume.
 6. The gas piston system of claim 5 whereinthe biased stop mechanism comprises a bearing in a biased position onthe plug and a complimentary seat on the gas block.
 7. The gas pistonsystem of claim 6 wherein the gas block comprises multiple seats capableof anchoring the plug in multiple positions.
 8. The gas piston system ofclaim 1 wherein prior to firing the gas pin head is biased to a positionabutting the plug.
 9. The gas piston system of claim 1 wherein the gaspin head comprises a concave surface facing the bore.
 10. The gas pistonsystem of claim 1 wherein the gas pin head comprises circumferentialchannels that introduce turbulence into gases passing between the gaspin head and the chamber portion.
 11. The gas piston system of claim 1wherein the second end comprises a cut-out that allows gasses passingbetween the gas pin head and the chamber portion to exit through thesecond end.
 12. The gas piston system of claim 1 wherein the chamberportion comprises an exhaust port obscured by the gas piston head in abiased position.
 13. The gas piston system of claim 12 wherein theexhaust port is obscured by the gas pin head prior to firing the firearmand is cleared by the gas pin head when the gas pin head is pushedtoward the second end.
 14. The gas piston system of claim 1 furthercomprising an impinging screw between the barrel and the chamber portionfor closing the pneumatic connection.
 15. An adjustable volume gas blockfor a firearm having a barrel and a gas pin, comprising: a plug having abore; the plug inserted into the gas block bringing the bore inpneumatic communication with the barrel; the gas pin biased against thebore forming an enclosed chamber; and wherein when the firearm is fired,gas enters the enclosed chamber, forcing the gas pin away from the bore;and wherein as the gas pin moves away from the bore a port is exposedallowing the gas to exit the gas block.
 16. The gas block of claim 15wherein the plug comprises a threaded member for rotatably engaging thechamber portion.
 17. The gas block of claim 15 wherein the plugcomprises a biased stop mechanism for preserving the volume of thechamber portion at a predetermined volume.
 18. The gas block of claim 17wherein the biased stop mechanism comprises a bearing on the plug and aseat on the gas block.
 19. The gas block of claim 18 wherein the gasblock comprises multiple seats for anchoring the plug in multiplepositions.
 20. A method of adjusting the timing of an automaticreloading firearm having a gas pin and a barrel, comprising the stepsof: providing a gas block having a chamber; installing a gas block onthe barrel; providing a pneumatic communication in the gas block betweenthe chamber and the barrel; providing a plug having a bore; insertingthe plug into the chamber; inserting the gas pin into the chamberopposite the plug; and firing the firearm, thereby causing a delay inthe automatic reloading action of the gas pin.